We propose to use a combinatorial chemistry approach to identify novel inhibitors of HIV-1 entry into cells. Our initial focus is on development of potential antiviral microbicides to prevent transmission, but this approach will yield agents that should also be useful for AIDS therapy. There is an urgent need for the development of novel and effective anti-HIV therapeutic agents. Current highly active antiretroviral therapy (HAART) for HIV-infected individuals is targeted against the viral protease and reverse transcriptase. However, limitations of HAARRT are toxicity, patient compliance and emergence of drug-resistant virus mutants. Accordingly, novel antiviral agents are needed to circumvent these serious limitations. For this project we are using combinatorial peptide libraries that consist primarily of D-amino acids or other small molecules. Our focus is on development of entry and/or attachment inhibitors that are targeted against HIV-1 envelope glycoprotein (gp120) and domains within the transmembrane subunit (gp41). In preliminary studies we have screened peptide libraries that were constructed predominantly with D-amino acids, and have identified many that bind to purified oligomerized gp140 of HIV-I. One of these compounds inhibits HIV-1 replication with a 50% inhibitory concentration (EC50) of 8 mu/M. Immediate goals of this project are: 1) to identify several additional entry inhibitors by screening of additional libraries, 2) to optimize the antiviral activity of the most promising of these inhibitors targeted to the envelope glycoprotein, and 3) to characterize mechanism(s) of antiviral activity and viral drug-resistance. Future plans are to test the drugs and strategies in our SHIV/rhesus macaque models for mucosal membrane transmission and AIDS.